One of the country's largest exam boards came close to not delivering A-level and GCSE results on time because of administrative failings, according to the results of an investigation published today.

In a letter to Mark Dawe, chief executive of the OCR (Oxford, Cambridge and Royal Society of Art) exam board, chief exams regulator Glenys Stacey, warns the consequences would have been “catastrophic - for candidates, for schools and universities and for the wider system”.

Ms Stacey, chief executive of Ofqual, adds: “The detrimental impact on public confidence in our system might have taken many years to overcome.”

OCR found itself in the dilemma as a result of a combination of the impact of government exam reforms and attempts to restructure its own marking system.

Firstly, as a result of withdrawing the opportunity for candidates to take exams in January and then resit them if they failed to get the grades they wanted, the exam board was faced with an extra 900,000 more scripts to mark in the summer of 2014.

In addition, it failed to predict that its own decision to move to online marking would lead to a big increase in the number of examiners dropping out of the marking system. By June 2014, the number dropping out was 850 compared to 517 at the same point the previous year and - by the end of July - this had risen to 1,684 compared to 1,285 (a 24 per cent increase).

This coincided with a restructuring of the system which removed the post of quality manager - the person an examiner in trouble would go to in order to sort it out. Instead, argues the investigation by Ofqual, it was left unclear who should take on this role.

Ms Stacey warned Mr Dawe that - if it had failed to meet its obligations - that it was “very likely a monetary penalty would have been imposed and in a very substantial sum”. “Had OCR in fact missed critical deadlines, we would not have hesitated to take serious and punitive regulatory action”.

In the event, by offering an incentive to markers to take on more scripts at the last moment and a closer scrutiny of the position the crisis was averted.

The report said of its investigation: “Fragmented governance at OCR was a critical weakness. OCR did not have a holistic understanding of the end-to-end process of marking through to the issue of results

“OCR needs a better understanding of the marking and awarding processes and how to make the assessor body more responsive.”

The potential crisis last year comes at a time when exam boards acknowledge they will have to take on thousands of extra markers in future to make former Education Secretary Michael Gove’s exam reforms work. OCR has estimated it will need at least 5,000 extra markers to cope with the switch from coursework in GCSE’s and A-levels to end-of-course tests.

Malcolm Trobe, deputy general secretary of the Association of School and College Leaders, said; “This will put a great deal of pressure on the system each summer and will mean many more markers are required.”

Kevin Courtney, deputy general secretary of the National Union of Teachers, added: “It is extraordinary that the report does not focus more on a wider concern - the imposition by Government of wide-ranging and substantial changes to the exam process at short notice with little or no consultation with the teaching profession and with little understanding of whether there was a need for change or what their effects would be.

“These ill-thought through and rushed changes led to circumstances that the awarding bodies and regulator both referred to last year as ‘volatile’. That should never be a word that we apply to important qualifications or a situation in which we put young people.”

A spokesman for the OCR board said: “Last summer’s marking did not go as smoothly as OCR would have liked. We welcome the regulator’s report as it confirms we delivered the results on time, took the right steps to improve our system resilience and that Ofqual did not need to take any regulatory action.”

Ms Stacey added: “We are pleased to see that OCR is in a very different position this year.”